How to make Blender render in real-time, as fast a computer game?
Use the Blender 2.80 Beta Version to get a new render engine called Eevee. The engine is lighter in performance consumption and can do real  time rendering even more realistically than the traditional Blender Render engine. Note: Before you open the old Blender file in 2.80 Beta, then keep a backup copy. Because once you open or create a project in Blender 2.80 Beta then you can't open it again in older versions. The physics engine is not yet completed. So, don't use the physics engine in Blender 2.80 Beta. If there is a bug or a problem in a feature of Blender 2.80 Beta,  then download the next day's version to get a better working version of Blender 2.80 Beta.